The effects on the radical scavenging activities and hepatic lipid levels in rats fed a high-fat diet (HFD) in the 70% ethanolic extract from Acer tegmentosum Maxim (ATM) were evaluated. Total phenol content of ATM was 168.60 mg catechin/g in the 70% ethanolic extract of Acer tegmentosum. The DPPH and ABTS radical scavenging activities were 18.32 mM TE/g and 32.25 mM TE/g, respectively. Food efficiency ratio was lower significantly in supplemented group with 150 mg/kg BW/day during 5 weeks (HFD+ATM) compared to HFD. Total cholesterol and triglyceride contents in liver tissue of HFD+ATM were lower significantly compared to those of the HFD. Supplementation of ATM significantly decreased lipid peroxide contents and increased radical scavenging activity in the liver tissue compared with that of HFD group. Moreover, the hepatocytes of HFD rats showed a typical fatty liver morphology showing the presence of cytoplasmic lipid droplets, whereas administration of ATM attenuated the number and the size of lipid droplets. In the liver tissue of ATM administrated HFD group, the mRNA levels of SREBP-1c, PPARγ, and FAS were decreased. Therefore, these results suggest that Acer tegmentosum extracts could have antioxidant activities and the hypolipidemic effects in liver tissue by its phenolic compounds.